Plug fuse and adapter



Oct. 22, 1935. e. R. BROWN 2,018,434

PLUG FUSE AND ADAPTER Filed on. 27. 1934 Kgi Inventor: IJ" 4/ George Brown,

S Attorney.

Patented Oct. 22, 1935 UNITED STATES PATENT OFFICE 2,018,484 TLUG FUSE AND ADAPTER G162: B. Brown. Stratford, Coma, assignor to oral Electric New York Company, a corporation of,

Application mm 21. mi. sci-m no. 150.254

' 'lciaiml. (CI. zoo-11s) '1 is dangerous as it eliminates any protection in a limited circuit and permits the line to be heavily overloaded. The overloading of a line may result in serious trouble at unexpected points in the event of a breakdown and short circuit.

15 In the drawing, Fig.1 is a sectional view showing an embodiment of the invention; Fig. 2 is an exploded view of Fig. i; Fig. 3 is a detail sectional view on line I-I' of Fig. 2; and Fig, 4 shows a modification.

2 Referring to the drawing, l indicates a typical fuse socket comprising a casing I of insulating material in which is contained a metal screw sheilI. Aterminalpostlpassesthroughthe bottom of the casing I and is separated from the shellbyaninsulatingwasherl.'1'hisis'tobe taken as typical of any suitable fuse socket.

The fuse comprises a housing I madeof insulating material. having a base 1 and a side wall I. A pin I which serves as one of the terminals ofthefusepassesthroughanopening II inthe bottomjwall of the base I. The pin I is encircled by a flange II which rests against a shoulder II. TheupperendofthepinIispeened over as indicated at II. This holds the pin 0 Y firmly in place. Extending downward from the base and formed integral therewith is a flange II which surrounds the flange II. The lower end of the pin I is threaded. A fuse wire ll is fastened to the upper end of the pinI by a drop of solder II. The wire II extends fromth'e upper end of the pin to the outside of the housing and fits in a groove il which extends down a the outside of the housing wall I.

Fitted overthe housing I and holding the fuse wire II inplace in the groove i1 is an outside casing II; Thecasing II is of a metallic'ma-- teri'ai and serves as'the second terminal. The

in upperendofthecasing'llisfastenedinanong cover ring II. A transparent window- II lies between the upper'end of thehousing I and the cover ring II. The lower end of the casing isspunover the lower end of the housing I as indicated at II. This holds the casing II,

window II. the fuse wire II and the cover ring II all firmly in position.

The adapter II comprises a screw shell II which is threaded to screw into the fuse socket shell I. Formed integral with the bottom of the side wall of the screw shell II is an inwardly extending flange II. Contained in screw shell II are four equally spaced spring contacts II. The outside surface of the contacts I6 engages the inside surface of the screw shell 23. 10 Each contact II is formed integral with a ring Ila which fits inside the shell II and is in contact with said shell. An inwardly extending flange II is formed integral with the ring 260. and rests on the flange II. The upper portion of the contacts II are sprung inwardly as indicated at II.

' Igagement with the shell II. A concentric shoulder II extends upward from the top of the disk II, andsurrounds the flange ll of the fuse. This forms a close fitting, overlapping, horizontal joint between the insulated portion of the plug and the fuse. A threaded opening II adapted to receive the pin I of the fuse extends through the center of the disk. A metal ring Ii is moulded I0 in the opening of the diskto strengthenthe the threads of the disk. .AsteelspringIIisfsstenedinarecess IIof the disk II. The end of the spring is pronged and extends through an opening IIa in the screw I5 shell II. The spring is reinforced by moulded material to prevent flexing in a clockwise direction. The steel spring II slopes in a direction suchthatthe adaptermaybethreaded intoa fuse socket. If an attempt is made to unscrew 40 the adapter from the fuse socket, the prongs of the spring bite into the shell and prevent its removal. Spring II' thus'serves as a lock to fasten the adapter in the fuse socket.

when a. fuse and adapter as heretofore deins scribed are to be tailed in a fuse socket for the first time, the pin I of the fuse is screwed into the opening II of the adapter. As the fuse is drawn down into the adapter, the casing II of. the fuse engages the inwardly sprung'portion of thecontacts II and a firm contact'is made between the adapter and the fuse. The combined fuse and adapter is then threaded into the shell.

I of the standard fuse socket. The adapter, once it screwed into the fuse socket, cannot be re- II moved due to the pronged steel spring which bites into the fuse socket shell. When the fuse is blown due to an overload, the blown fuse is screwed out of the adapter. A new fuse is then .threaded into the adapter and the line is again ready for use with the proper protection.

As was stated above, the practice of shorting around a fuse is a dangerous one. The usual procedure for shorting around a fuse, when the fuse blows out, is to remove the fuse, and insert into the fuse socket a coin, metal disk or other conducting material which will make a connection between the center contact and the outer shell of the fuse socket, and then replace the fuse to hold the connector in place. The circuit is then again completed but it is without protection from overloads. Many fires and serious accidents have resulted from this practice. The majority of people are ignorant of the dangers involved in shorting a fuse.

By the use of the adapter and fuse herein described, the shorting of a fuse is prevented. The middle contact of the fuse is the pin 9. In order for the pin 9 to engage the corresponding contact on the shell, it is necessary for the pin of the fuse to be threaded snugly into the insulated washer 28. When in this position, the insulating flange I4 of the fuse fits into the insulated shoulder 29 of the disk 28. Obviously, a metal disk cannot be used to short the fuse as it cannot reach the center contact and the fuse cannot be retained in place as the coin or other metal object would cover the threaded opening. The use of a metal washer having a hole in the center through which the pin would flt is also thwarted due to the overlapping of the flange I4 and the shoulder 29. It would be impossible to screw pin 9 in far enough to make contact with part 4 with a washer lying on shoulder 29. If the attempt were made to use a flexible metal like tinfoil, it would fail because when the flange I4 is screwed down inside shoulder 29, it would pull the tinfoil away from contact with the pin and thus prevent shorting. The pin 9 is made to thread into the hole 30 of the disk 28 with a tight enough fit that it would prevent any conductor being slipped down alongside of the pin.

The modification shown in Fig. 4 of the drawing is a fuse socket in which a fuse plug will fit without the use of a separate adapter. The socket comprises a base 34 in the center of which is an upwardly extending projection 35. In the center of the projection is an opening 36 which rests on the ring. Opposite sides of the horse shoe section are suitably fastened to the base. The outer end of the bar holds a binding screw 4|. Extending across the bottom of the base and covering the opening 36 is a second metal bar 42. The bar extends upward through the base to the top side. A binding post 43 is held by the portion of the bar at the top side. The bar is held in place by rivets 44.

Adapted to fit around the spring contacts 39 is a guard 45 which rests on the base and is held in place by a plurality of screws, one of which is shown at 46. The guard is provided with slots,

:- the walls of which fit around the binding posts 4i and 43 protecting them from outside contact. When placing the socket in use, the lines are fastened to the binding posts before the guard is put in place. After the lines are in place, the

guard is fastened down to the base and the socket 5 is complete. The socket functions similarly to the adapter described above in preventing short eircuiting around fuses.

The construction has the advantage that it is adapted to fit the fuse sockets now in common 1 use withoutalteration of the fuse sockets and, can be installed by anyone without difficulty. Also it is simple in construction and inexpensive to manufacture. The plug lends itself readily to automatic assembly as all parts are entered and 15 secured from one end. When completely assembled, the plug has no exposed and unsupported edges which can become dented and prevent good contact in the socket.

An important feature of the invention is the go arrangement of the spring contacts 25 which engage the-casing I8 of the fuse. The lower ends of the contacts are held firmly against the outer shell 23 by thev disk 28. The upper portions spring inward as indicated at 21, and when the 25 fuse is screwed in place, contact the outside shell of the fuse firmly, giving a good contact. As

these springcontacts are inside of the fuse socket,

they are not likely to become bent. Also, since the outer portion of the fuse is the metal casing 30 I8, it is not likely to become bent or damaged in handling. As a result, the fuse will always make proper contact with spring contacts 25 when screwed into place.

What I claim as new and desire to secure by Letters Patent of the United States is:

l. The combination with a fuse socket having two terminals, of an adapter comprising an outer shell which is in contact with one terminal of the fuse socket, a non-metallic disk positioned in said shell having an opening through its center, vertically extending contact means held between the disk and the outer shell, and means for locking said adapter in the fuse socket, and a fuse comprising an outer shell which is in contact with 45 the vertically extending contact means of the adapter, a pin which passes through the opening in the non-metallic disk and is in contact with the second terminal of the fuse socket, and fuse means connecting said pin and said outer shell.

2. The combination with a fuse socket having two terminals, of an adapter comprising an outer shell which is in contact with one terminal ofthe fuse socket, a non-metallic disk positioned in said shell having a threaded opening in its center, a metallic reinforcing ring in said opening in spaced relation to the surface of said disk, vertically extending contact means held between the disk and the outer shell and means for locking said adapter in the fuse socket, and a fuse comprising an outer shell which is in contact with the vertically extending contact means of the adapter, a threaded pin which screws into the threaded opemng in the disk of the adapter and is in contact with the second terminal of the fuse socket, and fuse means connecting the pin and the shell.

3. A fuse adapter comprisinga base of insulating material having a central opening for the passage of a fuse pin, a screw shell carried by the base, and spring contact fingers projecting upwardly from the base inside said screw shell.

4. A fuse'receiving member comprising a base of insulating material having a central opening for the passage of a fuse pin. an outside wall carried by the base. and spring contact fingers projecting upwardly .trom the base inside said outside wall.

5. A fuse socket comprising a base having an opening in its center adapted to receive a fuse pin, spring contacts extending upward from said base spaced equidistant from the opening, and a guard wail adapted to fit around the spring contacts.

6.Aiusesocketcomprisingabasehavingan' upwardly extending portion in its center which contains an opening. a contact bar adapted to cover the bottom of said opening, a metallic ring which aurroimds said upwardly extending portion, spring contacts projecting upward from said ring, a second metallic contact bar which holds the ring in place, and a guard surrounding the spring contacts and having slots, the walls of which flt around the ends of the contact bars.

7. A ruse receiving member comprising a base of insulating material having a reinforced opening in its center. an upwardly extending portion surrounding said opening, spring contacts ex- 19 tending upwardly from the base, and an outside wall surrounding said contacts.

' GEORGE R. BROWN. 

